Phonograph pickup



July 3, 1945. L. J. BOBB 2,379,782

PHONOGRAPH PICK-UP Filed Sept. 11; 1943 s Sheets- Sheet 1.

:3 h L w] a y PHONOGRAPH PICK-UP Filed Sept. 11, 1943 3 Sheets-Sheet 2L. J. 8055 v 2,379,782

Patented July 3, 1945 UNITED STATES PATENT OFFICE PHONOGRAPH moxur LloydJ. Bobb, Philadelphia, Pa., assignor to Philco Radio and TelevisionCorporation, Philadelphia, Pa., a corporation of Delaware ApplicationSeptember 11, 1943, Serial No. 502,003

15 Claims. (01. 179-100.)

This invention relates to electrical phonograph pick-ups.

One of the primary objects is to achieve high fidelity reproduction overa wide frequency band in a pick-up which can be manufacturedinexpensively.

Another object is to minimize record wear.

A third object is to provide a pick-up of simple construction which canbe used for playing both lateral-cut and hill and dale recordings.

Still another object is to provide a pick-up wherein the parts subjectto wear and tear can easily be replaced at little cost without thenecessity of returning the device to the factory.

A further object, is to provide a pick-up for use with lateral-cutrecordings wherein the stylus is so cushioned that dropping the pick-uponto the record will not be likely to damage either the stylus or therecord.

An additional object is to provide supplemental lateral stiffness whichdoes not materially affect the response of. thepick-upbut which bracesthe stylusagainst excessive lateral displacement. at

the end of each record play when the stylus is engaged by the spiraleccentric groove.

One of the special problems with which this invention deals is that ofexcessive wear of lateralsistance to small amplitude verticaloscillatory motion, with the result that stylus contact pressuregenerated by pinch-effect is greatly restricted.

At the same time the aforesaid resilient mounting functions as a pivotalsupport for the vibratory unit permitting the same to oscillatelaterally with only such resistance as is needed to provide essentialdamping. that it provides cushioning which is effective to preventinjury to the stylus and record which might otherwise result fromdropping the pick-up onto the record instead of carefully setting itthereon.

The vibratory unit is so constructed as to provide high rigidity coupledwith low mass wherecut records resulting from what is known aspinch-effect. This phenomenon arises from changes in width of the recordgroove due to lateral excursions of the recording stylus and manifestsitself during the playing of a lateral-cut record in the form ofivertically directed oscillatory force imparted to the styluswhichvertically directed oscillatory force causes corresponding increments ofcontact pressure between the stylus and record groove. The added contactpressure thus generated increases friction and.

thereby accelerates record deterioration.

The increments of contact pressure due to pinch-effect can come intobeing only tothe extent that complementary reactionary force isdeveloped. In other words, it is only in proportion to the opposingreaction set up by the stylus that pinch-effect can cause contactpressure to be generated. If the stylus were toyield without offeringany reaction (a condition impossible of fulfillment) there would be noconsequential con--- fore all movements of the stylus, both lateral andvertical, imparted thereto by the record, are transmitted faithfully tothe moving coil which is thereby enabled to generate voltagecorresponding accurately to the recording.

Another feature of this invention has to do with the playing oflateral-cut and hill and dale recordings alternatively, with the samepick-up. The aforementioned vibratory unit is so con: structed that itwill respond with equal facility to either type'of recording; but to beeffective it is necessary that the magnetic field be altered whenever achange is made from lateral-cut to hill and dale recordingsand viceversa. 1'. have devised a field structure wherein the magneticpolarities can be altered very quickly and! easily to adapt the pick-upfor the playing of either type of recording alternately.

Still another feature of special advantage is a unique self-containedvibratory unit which can easily be withdrawn and replaced and which ischaracterized by extremely low inertia and high rigidityfactors whichare vital to high fidelity and long record life.

An additional feature which has proved of considerable value consists inthe provision of electrical leads for the moving coil which are encasedbetween flat strips of parchment paper or the like to provide stiffness,and so anchored that the This feature also is of value in saidleads andpaper casing function to restrain the vibratory unit against excessive.rotation at the end of each record play when the stylus is engaged bythe spiral eccentric groove-but without introducing stiffness adverselyaffecting the response of the pick-up.

Some preferred embodiments of this invention are illustrated in theaccompanying drawings,

wherein:

Fig. 1 is a front elevational view of an electrical pick-up embodyingthe principal features of the invention;

Fig. 2 is a side elevational view of the same;

Fig. 3 is a top plan view of the same;

Fig. 4 is a bottom plan view of the device;

Fig. 5 is an enlarged fragmentary sectional view showing the vibratoryunit more clearly;

Fig. 6 is a sectional view taken along the line 6-8, of Fig. 5;

Fig. 7 is a sectional view taken along line '|--l of Fig. 6;

Figs. 8 and 9 are views, corresponding gener-' ally to Figs. 5 and 6, ofa modification having a different form of resilient mounting;

Fig. 10 is a. perspective view of the mounting element;

Figs. 11 and 12 are further views of still another modification with adifferent form of resilient mounting;

Fig. 13 is a perspective view of the mounting structure;

Fig. 14 is a sectional view of another embodiment taken along line lll4of Fig. 16;

Figs. 15, 16 and 17 are end, top plan, and bottom plan views,respectively of the same;

Fig. 18 is an enlarged fragmentary sectional view showing the vibratoryunit and its mountins;

Fig. 19 is a perspective view showing the mounting elements for saidunit; and

Fig. 20 is an enlarged cross-sectional view of a fiat cable employedin'the device.

Referring first to Figs. 1 to 4, inclusive, reference numeral lidentifies the free end of a tone arm which may be pivoted at its remoteend (not shown) to swing in a horizontal plane and also in a verticalplane. To' said arm'is attached a pick-up 2 whereof the stylus 3 isintended to engage the groove of a recordingwhich recording may beeither lateral-cut or of the hill and dale variety.

The pick-up comprises a magnetic field structure identified as a wholeby numeral 4 and a vibratory unit identified as a whole by numeral 5.

Magnetic field structure 4 (see Fig. 1) includes a soft iron member 6, apair of soft iron polepieces I and 8, a spacer block 9 of brass or othernon-magnetic material, a permanently magnetized block I0 and a secondpermanently magnetized block ll. Blocks i0 and II preferably are made ofa magnetic material such as Alnico but can be ordinary magnet steel.Block H) serves as a spacer between member 6 and pole-piece I and isclamped between those members by means of a pair of brass screws l2 andI3. Non-magnetic spacer block 9 is clamped between member 6 andpole-piece 8 by a pair of screws I4 and I5 which should be of non-magnetic material. v

Magnetized block II is rotatably mounted on the shank of a stripper boltl6 which is threaded into block 9. The threaded end of said bolt is ofsmaller diameter than the shank, and the head of said bolt does not bindblock II. The

and dale recordings.

latter adheres tightly to the contacting ends of member 8 and pole-piece8 by reason of magnetic attraction, but it can be rotated about bolt l6as a center without much efiortespecially if the contact surfaces arelubricated.

role-piece I has a fixed magnetic polarity whereas the polarity ofpole-piece 8 is reversible and depends upon the position of block ll.Rotating said block degrees reverses the polarity of pole-piece 8. Thus,the two polepieces 'I and 8 may be of the same polarity or of oppositepolarity. When the two pole-pieces are of opposite polarity magneticflux will flow from one to the other via the center pole 6 whichconstitutes an integral part of member 5. When the two pole-pieces areof like polarity the fiux will follow separate parallel magneticcircuits having a common path through the center pole 6'.

For playing lateral-cut recordings the two pole-pieces 1 and 8 must beof opposite polarity. For playing hill and dale recordings the twopole-pieces must be of like polarity in which case the center poleacquires a definite polarity opposite to that of pole-pieces I and 8. Achangeover of the pick-up from lateral-cut to hill and dale requiresonly a 180 degree rotation of block II. The vibratory unit is at alltimes conditioned to respond to either lateral-cut or hill and dalerecordings. The oscillatory movements of the vibratory unit when playinglateral.- cut recordings is indicated by the arcuate doubleheaded arrowsll (Figs.,1 and 5). The oscillatory movements of said unit when playinghill and dale recordings is indicated bythe vertical double-headed arrowl8.

As previously stated, one of the features of this invention resides inthe mounting of the vibratory unit in such manner that it offers verylittle resistance to small'amplitude upward movement in response topinch-effect while at the same time not interfering with lateraloscillatory rotation of the unit which must take place concurrently withthe up and down movements resulting from pinch-effect. This samecharacteristic renders the pick-up efficient also in the playing of hilland dale recordings.

How this is accomplished is illustrated in Figs.

5, 6 and '7. while alternative arrangements are shown in the subsequentfigures 8 to 19 inclusive.

Referring now to Figs. 5, 6 and 7, vibratory unit 5 is seen to comprisea cup-like body member l9 made of thin sheet material such as parchmentpaper or aluminum. The upper part l9a of the body member is cylindricaland annular whereas the lower portion l'llb is conical. Mounted at theapex of the cone and firmly secured thereto is a stylus mounting 20 inwhich is embedded the stylus 3usually a sapphire. Wound upon and carriedby the cylindrical annular portion l9a is a coil of fine wire 22. This'is known as the moving coil. The vibratory unit thus described haslittle mass and is distinctly rigid so that the vibrations of stylus 3are transmitted to the moving coil with, little loss throughout a widefrequency band. The response curve is remarkably fiat from the lowestaudible frequencies up to about ten kilocycleswhich means fidelity of ahigh order. The rigidity of body member l9 holds true with respect toboth lateral oscillations, such as are imparted to it in the playing oflateral-cut recordings, and vertical oscillations such as are impartedto it in the playing of hill This likewise holds true with respect tovertical oscillations imparted to face of the body member.

aware: p

and 28 there is substituted a single U-shaped soft the stylus by reasonof pinch-eilfect in the playing of lateral-cut recordings. It will beapparent that vertical motion imparted to the vibratory unit bypinch-effect inthe course of playing lateral-cut records does not resultin the generation of voltage or current.

As clearly depicted in Figs. and 6, the moving coil encircles the lowerend-of center pole 6' and is disposed in two magnetic flux-traversinggaps 23 and 24 formed by pole-pieces 'l and 8 conjointly with centerpole 6'.

The center pole functions not only as such (when playing "hill and dalerecordings) but also as a magnetic core for the moving coil when playinglateral-cut recordings, and as a supporting element for vibratory unit5, which is suspended thereon.

The means whereby the vibratory unit is attached to center pole 6' andcentered thereon comprises a pair of highly resilient inserts 25 and 26,preferably formed of soft rubber or other material having commensurateresilience. These are somewhat elongated, as shown in Figs. 5 and 6, andrectangular in cross-section, as shown in Fig. 7. These inserts aresecured in slots cut inopposite sides of center pole B and preferably 7cemented in place.' Circumferentially the two inserts engage body memberit along the internal surface of cylindrical portion l9a, and'the lowerends of the inserts are preferably beveled, as shown, to conform to theinternal conical sur- The inserts engage the body member with enoughpressure to ensure its retention against gravity, but preferably not sotightly but that the unit can be withdrawn quite easily when replacementbecomes necessary. Thus the vibratory unit is free of permanentattachment and is held only by the frictional engagement thereof withthe inserts.

The soft rubber inserts are positioned as shown in Fig. 7 at rightangles to the pole-pieces, and they function as resilient self-dampingpivots about which the vibratory unit rotates oscillatorily whenactuated by a lateral-cut record. The approximate pivotal center isindicated in Fig. 5. Thus the vibratory unit oscillates about thevertical axis of the device extending upwardly from the stylus.

The rubberfrom which the inserts are molded or cut is preferably quitesoft and yieldable and generally homogeneous. Consequently the insertsoffer very little impediment to vibratory rotation of the unit. Also,the resiliency of the inserts is such that small amplitude verticalmovements of the vibratory unit. meet with exceedingly littleopposition. This factor, in conjunction with the small mass of thevibratory unit, minimizes reaction to vertical vibration due topinch-effect. At the same time the vertical resiliency of the insertsrenders the pick-up well adapted to the playing of hill and dalerecordings.

of tone arm I may, of course, be counterbalanced to ensure that thestylus pressure is, not greatly in excess of what is needed to keep thestylus in the record groove. I have found that stylus pressures of theorder of 0.5 ounce are ordinarily sufficient. v

The structure of Figs. 8 to 10 is exactly the same as that of Figs. 5 to7 except for the substitution of a modified form of soft rubber insertand such alterations as are needed to accommodate the modified insert.The vibratory unit is unchanged, but in place of the two inserts 2-5 Theweight of the field structure, as well as that rubber insert 21. Thisinvolves the provision of a diametrical slot 28 extending across thebottom end of center pole 6?. Insert 21, functions in the same manner aspreviously described with respect to inserts and 26.

Another modification is illustrated in Figs. 11 to 13. Here thevibratory unit remains unchanged, but a third form of soft rubber insertis employed. This comprises a strip 29 of rectangular cross-sectionextending crosswise through a slot 30 milled in the bottom face of thecenter pole. Two slots BI and 32 preferably of slightly greater widththan that of insert 29 (see Fig. 13) are milled in opposite sides of thecenter pole. These latter slots afford clearance so that the two ends ofinsert 29 overhang the. ends of slot 30 in the manner of cantilevers.This arrangement increases somewhat the vertical resiliency of themounting and makes it possible, if desired, to use rubber which issomewhat less resilient than would otherwise be indicated.

Each of the aforementioned three forms of rubber inserts serve toprovide resilient pivots which are highly yieldable with respect to bothrotational oscillations and vertical oscillations of the vibratory unit.Thethree forms shown are substantially gquivalent and it will beapparent that there are numerous further modifications possible withinthe scope of the invention.

There is shown in Figs. 14 to 20, inclusive, a pick-up embodyin thepresent invention but designed for use with lateral-cut recordingsexclusively. Here the vibratory unit 5 is substantially the same aspreviously described and the rubber inserts 33, 34 supporting thevibratory unit are substantially like those of the first-describedembodiment. The center member 35 functions as a magnetic core for thevibratory unit and as: a supporting element; but it is not a pole-piecesince it is anchored at its upper end in a block 36 of non-magneticinsulating material into which the shank 35a is pressed. The fieldmagnet structure comprises a permanently magnetized block 3! secured byscrews 38, 39 between two pole-pieces 40. M. As shown most clearly inFigs. 15 and 17 these pole-pieces partly encircle and arespaced from thecenter member 35 to form a pair of arcuate magnetic flux-traversing gaps42, 43 in which is situated the moving coil.

A featfire of the device (applicable also to the previous y describedembodiments) is the flat ribbon-like cable 44shown in cross section on agreatly enlarged scale in Fig. 20. This cable interconnects the two endsof the moving coil with soldering terminals 45, 46 and comprises a pairof spaced wires 41, 48 interposed between two .005" thick parchmentpaper laminae 49, 50 cemented together and forming a rather stiff ribbonapproximatelyone-eighth inch wide. The upper end portion of the cable isattached at 5| (see Fig. 14) by means of a suitable adhesive, to theblock 36. and the lower portion 52 of said cable extends horizontally toeffect a junction with the moving coil. The pivotal center about whichthe vibratory unit oscillates rotationally is below the point ofconnection between cable 44 and the moving coil, and said cable has suchstiffness that it impedes rotation of the vibratory unit when theamplitude ofrotation has gone beyond the maximum normally imparted bythe record undulations. The cable does not become materially effectiveas a stiffening agent so as to influence the response of the pick-up;but when a considerably larger amplitude of rotational force is impartedto the vibratory unit the cable becomes effective as a mechanicalresistance medium.

Thus, at the end of each record play when the stylus is engaged by thespiral eccentric groove the lateral force imparted thereto isconsiderably greater than the maximum rotational force brought to bear.upon the stylus by the record undulations during the playing of arecording. The supplemental stiffness provided by cable 44 becomeseifective to a measurable degree only when this greater force tending torotate the vibratory unit excessively comes into being; that is to say,only at the end of each record play.

Although a number of embodiments of the invention have been illustratedand described for purpose of disclosure, it will be seen that theinvention is not limited thereto but is capable of other embodiments andmodifications.

I claim:'

1. In a phonograph pick-up having a vertical axis, a magnetic fieldstructure including a pair .of opposed spaced poles at either side ofsaid axis,

a supporting element interposed between said poles and spaced therefromto form two narrow magnetic flux-traversing gaps disposed at either sideof said axis,a vibratory unit comprising a body member, a moving coiland a stylus, said body member being formed of thin sheet material andincluding a coil-carrying portion encircling said supporting element anddisposed in both said gaps, said coil being wound on and carried by saidcoil-carrying portion and disposed in said gaps, said stylus beingdisplaced from said coil lengthwise of said vertical axis, said bodymember including a second portion rigidly connecting said stylus withsaid coil-carrying portion and operative to transmit vibratory movementsof said stylus to said coil-carrying portion and thence to said coil,and resilient means interposed between said supporting element and theinterior of said body member and functioning to attach said vibratoryunit to said supporting element, said resilient means engaging said bodymember at opposite points interiorly'of said coilcarrying portion andserving as resilient pivots to permit said vibratory unit to oscillaterotationally in response to lateral oscillatory movements of saidstylus, said resilient means being further characterized in that ityields readily to small amplitude oscillatory movements of said unit inthe direction of said vertical axis.

2. In a phonograph pick-up having a vertical axis, a magnetic fieldstructure including a pair of opposed, spaced poles at either side ofsaid axis, a supporting element of magnetic material interposed betweensaid poles and spaced therefrom to form two narrow magneticflux-traversing gaps disposed at either side of said axis, a vibratoryunit comprising a bodymember, a moving coil and a stylus, said bodymember being formed of thin sheet material and including a cylindricalannular portion encircling said supporting element and disposed in bothsaid gaps, said coil being wound on and carried by said cylindricalannular portion and disposed in said wound on and carried by saidannular portion gaps, said stylus being disposed concentrically withsaid coil and displaced from said coil lengthwise of said vertical axis,said body member including a conical portion rigidly connecting saidstylus with said cylindrical portion and operative to transmit vibratorymovements of said stylus to said cylindrical portion and thence to saidcoil, and resilient means interposed between said supporting element-andthe interior of said body member and functionin to attach said vibratoryunit to said supporting element, said resilient means engaging said bodymember at opposite points interiorly of said cylindrical portion andserving as resilient pivots to permit said vibratory unit to oscillaterotationally in response to lateral oscillatory movements of saidstylus, said resilient means being further characterized in that ityields readily to small amplitude oscillatory movements of said unit inthe direction of said vertical axis.

3. In a phonograph pick-up having a vertical axis, a. magnetic fieldstructure including a pair of opposed spaced poles at either side ofsaid axis, a supporting element interposed between said poles and spacedtherefrom to form two narrow magnetic flux-traversing gaps disposed ateither side of said axis, a self-containned vibratory unit comprising abody member, a moving coil and a stylus, said body member being formedof thin sheet material and including a coil-carrying portion encirclingsaid supporting element and disposed in both said gaps, said coil beingwound on and carried by said coil-carrying portion and disposed in saidgaps, said stylus being disposed concentrically with said coil anddisplaced from said coil lengthwise of said vertical axis, said bodymember including a second portion rigidly connecting said stylus withsaid coil-carrying portion and operative to transmit vibratory movementsof said stylus to said coil-carrying portion and thence to said coil,and resilient means interposed between said supporting element and theinterior of said body member and functioning to attach said vibratoryunit to said supporting element, said supporting element being slottedto receive said resilient means, said resilient means engaging said bodymember at opposite points interiorly of said coil-carryin portion andserving as resilient pivots to permit said vibratory unit to oscillaterotationally in response to lateral oscillatory movements of saidstylus, said resilient means being further characterized in that ityields readily to small amplitude oscillatory movements of said unit inthe direction of said vertical axis.

4. In a phonograph pick-up having a vertical axis, a magnetic fieldstructure including a first pole member constituting a supportingelement, and at least one additional pole member forming a magneticflux-traversing gap with said first pole member, a vibratory unitcomprising a cuplike body member, a moving coil and a stylus, said bodymember including an annular upper portion traversing said gap andencircling said first-mentioned pole member, said coil being anddisposed in said gap, said stylus being situated on said vertical axisand displaced from said coil lengthwise of said axis, said stylus beingrigidly attached to and carried by said body member, and resilientinsert means within said body member and interconnecting said vibratoryunit with said first pole member, said insert means constitutingresilient pivots for said vibratory unit and characterized by resiliencypermitting said vibratory unit to oscillate vertically with littlerestraint relatively to said pole members, and also to oscillaterotationally with little restraint.

5. In a phonograph pick-up having a vertical axis, a supporting element,resilient means carried by said supporting element, a stylus, said resilient means being constructed and arranged to function as a pivotalsupport for said stylus and apropos permitting said stylus to oscillateireely both lat erally of said axis and parallel thereto, means defininga magnetic flux-traversinggap encircling said supporting element,amoving coil disportion terminating at its base extremity in an annulartube-like portion on which said coil is wound, said cone portionbeingconnected at its apex to said stylus, said body memberbeingoperative to transmit at least the rotational oscillations of saidstylus to said coil, said resilient means being located interiorly ofsaid annular tube-like portion and serving as a, pivotal support forsaid body member and coil.

6. In a phonograph pick-up having a vertical axis, a supporting element,a pair of resilient elongate inserts situated at diametrically oppositesides of-said element and projecting therefrom laterally of said axis,said inserts being seated in slots formed in said element and extendingtory unit comprising a cup-like body member, a moving coil and a stylus,said body member having a tube-like annular upper portion and a cup-likeconical lower portion to the apex of which said stylus is rigidlyconnected, said coil being Wound on and carried by said upper portion,said inserts frictionally engaging the interior periphery of said upperportion at diametrically opposite points and thus forming elongatepivotal supports for said body member, said inserts also engaging theconical interior surface of said lower portion to afford abutment meansfor said body member with respect to upward movements thereof.

7. In a phonograph pick-up having a vertical axis, a supporting element,said element being slotted diametrically across its lower end and alsoslotted lengthwise at two opposite sides upwardly from the slot formedin its lower end, a U-shaped resilient insert seated in the slots formedin said element and secured therein, said insert having diametricallyopposite leg portions projectingradially from said element and alsoextending lengthwise of said element and parallel to said axis, said legportions constituting a pair of pivotal supports, a vibratory unitsuspended on said pivotal supports and comprising a cup-like body memberof thin sheet material the upper portion of which is frictionallyengaged internally by said pivotal supports, said vibratory unitincluding a moving coil wound on and carried by the upper portion ofsaid body member, and a stylus secured to the lower extremity of saidbody member, said resilient insert being yieldable to both vertical androtational oscillatory movements of 'said unit.

8. In a phonograph pick-up, a supporting element having a slot extendingdiametrically across itslower end, an elongate resilient insert seatedin said slot and extending diametrically of said element, the ends ofsaid insert projecting radially from said element in oppositedirections, and a vibratory unit comprising a cup-like body member madeof thin sheet material, the upper portion of said body member beingannular and tube-like and encircling the ends of said insert and infrictional engagement therewith, the lower portion of said body memberbeing conical and depending from said upper portion, a stylus rigidlyattached to the lower terminus of said conilengthwise thereof parallelto said axis, a vibrasaid upper portion, said insert serving as apivotal support for said vibratory-unit and as a x upward moveyieldableabutment with respect to ments of said unit.

- 9. An electric phonograph pick-up operative with both lateral-cut and"hill and dale" recordings, alternatively, and comprising a magneticfield structure in combination with a vibratory unit, said fieldstructure including two distinct magnetic circuits having a commonportion defined by a center pole, each of said circuits including anindividual pole spaced from said center pole to form an individual gap,each of said circuits including an energizing permanent magnetindividual thereto and determinant of the polarity of its saidindividual pole, at least one of said magnets being bodily reversiblefor reversing the polarity of its associated individual pole, saidvibratory unit comprising av moving coil disposed in said gaps and astylus for actuating said coil, said vibratory unit being pivoted torotate oscillatorily in response to actuation of said stylus bylateral-cut recordings, said vibratory unit being resiliently mounted topermit straight-line oscillation thereof transversely of said gaps inresponse to actuation of said stylus by hill and dale recordings.

10. An electric phonograph pick-up operative with both lateral-cut andhill and dale recordings, alternatively, and comprising a magnetic fieldstructure in combination with a vibratory unit, said, field structureincluding twodistinct magnetic circuits having a common portion deiinedby a center pole, each of said circuits having an individual polespacedfrom said center pole to form an individual gap, each of saidcircuits including an energizing magnet individual thereto anddeterminant of the polarity ofits cal portion, and a coil wound on andsupported said individual pole, at least one of said means beingpivotally mounted to facilitate rotation thereof for reversing thepolarity of its associated individual pole, said vibratory unitcomprising a moving coil disposed in said gaps and a stylus foractuating said coil, said vibratory unit being pivoted to rotateoscillatorily in response to actuation of said stylus by lateral-cutrecordings, said vibratory unit being resiliently mounted to permitstraight-line oscillation thereof transversely of said gaps in responseto actuation of said stylus by hill and dale recordings.

1'1. In a phonograph pick-up, a moving coil, means pivotally supportingsaid coil for rotational oscillation in a magnetic field, a stylus forrotationally oscillating said coil in conformity with record grooveundulations, said coil normally functioning to generate voltagecorresponding to said record groove undulations, and a relatively stillribbon-like element anchored at one portion and connected with said coilat a point spaced from said anchored portion, said element beingoperative to stiffen said coil against rotation in excess of whatisneeded in the performance of its aforementioned normal function, saidelement exercising little or no restraint upon said moving coil inopposition to the vibratory actuation thereof efiected by the recordgroove undulations.

12. In a phonograph pick-up, a moving coil, means pivotally supportingsaid coil for rotational oscillation'in a magnetic field, a, stylus forrotationally oscillating said coil in conformity with record grooveundulations, said coil normally functioning to generate voltagecorresponding to said record groove undulations, and a, fiat ribbon-likecable leading to said moving cable comprising a plurality of parallelcoil, said conduc strips oi'iinsulating material-constituting, con-.

Jointly, casing 'ior-said conductors, said conductors ing connected eachat one end to said coil, said cable being anchored at a point spacedfrom said coil, said casing extending from said anchorage pointsubstantially to said coil and having enough intervening length topermit said coil to osc llate freely in the performance oi its normalfunction, said cable being effective to stiflen said coil againstrotation in excess of what is needed in the performance of said normalfunction.

13. In a phonograph pick-up oi the moving coil p a supporting element. acoil-supporting member encircling said element in spaced relationthereto, a magnetic field structure arranged to provide aflux-traversing gap in which the coil is disposed, resilient meanscarried by said sup- I porting element and engaging said coil-supportingmember at opposite points so as to provide resilient pivots for saidmember, whereby the latter may oscillate about said pivots to move saidcoil in the flux-traversing gap, and a stylus attached to saidcoil-supporting member tooscillate the same- 14. In a phonographpick-up, a magnetic field structure including a pair of spaced poles, asupasvavaa porting element interposed betweensaid poles and spacedtherefrom to form narrow fluxtraversing gaps, a vibratory unitcomprising a body member, a moving coil and a stylus, said body memberincluding a coil-car yin p rtion encircling said supporting element anddisposed in said gaps, and resilient means carried by said supportingelement and projecting therefrom at opposite points and frlctionallyengaging the type, a supporting element; a cup-like member having acoil-supporting portion encircling said element in spaced relationthereto, a magnetic field structure arranged to provide aflux-traversing gap in. which the coil is disposed; resilient meanscarried by said supporting element and engaging said member interiorlyof its coil-sup porting portion at opposite points so astntprovideresilient pivots for said member, whereby the latter may oscillate aboutsaid pivots to move said coil in the flux-traversing gap, and a stylusattached to said cup-shaped member in substantial alignment with theaxis thereof.

' LLOYD J. BOBB.

